The present invention is related to an improved pneumatic buffing machine, and more particularly to a pneumatic buffing machine in which the housing and the skirt are separately formed and the skirt shade is directly screwed into the housing without using any screws.
FIGS. 5 and 6 show a conventional pneumatic buffing machine. The buffing machine includes a housing 5 integrally having a skirt 51 for fitting with a dustproof shade 55. The housing 5 has an internal chamber 52 in which a pneumatically driven motor set 53 is mounted. A control seat 54 is disposed on one side of the housing. 5 for controlling intake and exhaust. Accordingly, the air is controlled to enter the chamber 52 of the housing 5 for driving the motor set 53. The motor set 53 further drives a grinding disc 56 at the bottom end of the motor set 53 for buffing a work piece.
A fixing member 6 is screwed in the chamber 52 of the housing 5 for fixing the motor set 53 in the chamber 52. The fixing member 6 is formed with an outer thread 61, while the wall of the chamber 52 is formed with inner thread 521 above the skirt 51, whereby the fixing member 6 can be screwed in the chamber 52 for stopping and fixing the motor set 53 in the chamber 52. The circumference of the fixing member 6 is formed with several notches 62 for a tool to screw the fixing member 6.
The housing 5 is integrally formed with a-skirt 51. Therefore, when screwing the fixing member 6 in the chamber 52, it is necessary to deeply extend the fixing member 6 into the housing 5 and then screw the fixing member 6 in the inner thread 521. It is hard to directly screw the fixing member 6. A special wrench 7 having two chucking pillars 71, 72 is needed for wrenching the fixing member 6. The chucking pillars 71, 72 of the wrench 7 are inserted into the notches 62 of the fixing member 6 as shown in FIG. 7 for screwing the fixing member 6 in the chamber 52. When extending the fixing member 6 into the chamber 52, the fixing member 6 tends to deflect. Therefore, it is hard to assemble the fixing member 6 with housing 5.
Moreover, in order to reduce vibration of the motor set 53 in operation, two rubber sleeves 532 are respectively fitted around two ends of the casing 531 of the motor. The rubber sleeves 532 contact with the housing 5 and the fixing member 6 for achieving a damping effect. However, when locked in the chamber 52, the fixing member 6 tightly abuts against the rubber sleeves 532. Therefore, the damping effect will be reduced or even the rubber sleeves 532 will be broken.
Furthermore, the housing 5 is integrally formed with the skirt 51 so that the housing 5 has a considerable length. In the case that the housing 5 is made of plastic, the elongated housing 5 will increase the deformation of the injected plastic. Therefore, the housing 5 tends to deform. This will affect the assembly of the components in the housing 5.
FIG. 8 shows another pneumatic buffing machine in which the housing 9 and the skirt 8 are separately formed. The skirt 8 is fixed under the housing 9 by means of screws. The top face of the skirt 8 is formed with several through holes 82. The bottom end of the housing 9 is formed with several thread holes 91 corresponding to the through holes 82. Several screws 81 are passed through the through holes 82 and screwed into the thread holes 91 to lock the skirt 8 under the bottom of the housing 9. The motor set 92 is fixed at top end of the skirt 8.
The skirt 8 is fixed under the housing 9 by means of screws 81. Therefore, the section of the housing 9, where the thread holes 91 are formed must have a certain thickness. With respect to a small-size pneumatic buffing machine, the housing 9 has a relatively thin wall on which the thread holes 91 can be hardly formed. Under such circumstance, it is impossible to fix the skirt 8 under the housing 9 by screws 81. Moreover, in the case that the wall of the housing 9 is formed with the thread holes 91, the thickness of the wall will be reduced to minify the strength of the housing 9.